Drying characteristics and kinetics solar drying of Moroccan rosemary leaves

Abstract

Water contained in foods allows the proliferation of microorganisms and the development of chemical reactions that deteriorate the product. This experimental study is focused on the influence of drying parameters on water loss of fresh rosemary leaves. It presents the experimental study results of the drying kinetics. The drying kinetics of rosemary was carried out in an indirect active solar dryer with a separate solar collector and a drying unit.The drying kinetics was studied for four different air temperatures (50, 60, 70 and 80° C) and two air flows drying (300 m3/h and 150 m3/h) for an ambient temperature in the range of 26–37 °C. The increase of temperature reduced drying duration. The drying time variation according to the drying air flow rate is important for lows temperatures, but not significant for highs temperatures.The experimental results are used to determine the characteristic curve drying. Out of nine models tried for simulation, Midilli kucuk model was found as best fitted thin layer drying model when simulation was done for all the drying data. In the ranges covered, the effective moisture diffusivity values (Deff) were obtained between 9.74 10−11 m2/s and 1.48 10−10 from the Fick’s diffusion model. The Arrhenius relation, with an activation energy value of 54.37 kJ/mol, expressed the temperature effect on the diffusion coefficient.